Protein phosphorylation is an essential part of the activating and regulatory processes in the functioning and responses for a variety of cell. Only little attention has been paid to protein phosphorylation in neutrophils despite the importance of this leukocyte in defense against infection and in number of allergic and nonallergic tissue-damaging inflammatory reactions. A full scale study of the nature and role of protein phosphorylation induced by chemotactic factor stimulation of rabbit peritoneal neutrophils has been initiated. The ultimate purpose of the proposed investigation is to identify, isolate and characterize those proteins which are phosphorylated when neutrophils are stimulated by chemotactic factors and the respective protein kinase for which they are responsible. Attempts will be made to identify the function of the phosphorylated proteins, the role the phosphorylation plays in these respective functions and what role the proteins and their phosphorylation play in neutrophil stimulus-response coupling. The present application is devoted largely to the first part of the ultimate aim: the identification of the proteins that are phosphorylated and the kinases which catalyze the phosphorylation. For these purposes, the following specific aims are proposed. (1) To continue to define the varieties of protein (kinases, tyrosine protein kinase, protein kinase C and others) and their respective substrates in various subcellular fractions of neutrophils. (2) To continue to define the phosphoproteins, the phosphorylation levels of which are regulated by chemotactic factors (fMet-Leu-Phe) and phorbol ester (PMA) in intact neutrophils and to correlate the phosphorylation of these phosphoproteins to the physiological responses of neutrophils. (3) To identify and characterize the molecular components (proteins kinases and their substrates) of the physiologically important phosphorylation systems in neutrophils. (4) To study the effect of guanine nucleotide on the activity of membrane associated protein kinases. (5) To search for the possible phosphoylation and regulation of the fMet-Leu-Phe receptor by a receptor-specific protein kinase. (6) To study the possible phosphorylation and regulation of vimentin and actin binding protein (acumentin and profilin) by various neutrophil protein kinases.